Bobbin threading device for sewing machines



United States Patent References Cited UNITED STATES PATENTS 12/1906 Berger..........................

[51] Int. D051) 59/00 [50} FieldofSearch...............

Inventor Kristen l-ledegaard- Gentofte, Denmark 743,833

Appl. No. [22] Filed July 10, 1968 Patented Oct. 13, 1970 [73] Assignee G.M. Pfa1fA.G. Kaiserlautern Pfalz, Germany a firm l12/186X 112/186 ll2/186X 112/186 906,987 12/1908 Angus............... 2,808,795 10/1957 Wortham 3,125,973 3/1964 Berneruseta1.r.............

Primary Examiner-H. Hampton Hunter Attorney-Robert H. Jacob [32] Priority July 13, 1967 [33] Germany [54] BOBBIN THREADING DEVICE FOR SEWING MACHINES 9 Claims, 8 Drawing Figs.

ABSTRACT: A bobbin threading device comprising a pair of 112/ 186, threader shafts each supporting a catcher and alternately 1 12/218 operative to thread a bobbin on one of the catchers.

Patented Oct. 13, 1970 Sheet 2 013 INVENTOR. 169/5 727V 19685634144 0 ACT Patented Oct. 13, 1970 Sheet INVENTOR. K/Q/SifN/VfMG/MfD 1 BOBBIN THREADING DEVICE FOR SEWING MACHINES BACKGROUND OF THE INVENTION The invention relates to bobbin threading devices for sewing machines. More in particular. the invention provides a threading device having two independently driven threading shafts, each having a catcheneach of which is adapted to be coupled with a bobbin.

In exchanging the bobbins of a sewing machine the seamstress must remove the top shell or casing with the empty bobbin by hand from the catcher or looper of the sewing machine. Thereupon she removes the empty bobbin from the shell and inserts a threaded bobbin in lieu thereof. She guides the thread manually in a slot in the upper shell and then leads it below the tension spring and then is able to insert the top shell with the threaded bobbin into the looper.

Thus, in known threading assemblies the empty bobbin has to be put aside upon its removal from the top shell and first the full bobbin has to be withdrawn from the bobbin stud before the empty bobbin can be placed upon this stud.

All of these manipulations require a certain expenditure of time which is lost from the effective sewing time. In pursuit of decreasing nonproductive lost time, it is an object of the invention to speed up and simplify the manual exchanging of bobbins thus as it is still generally used, disregarding, of course, the expensive automatic bobbin exchange assemblies which can only be economically justified in connection with sewing machines that operate fully automatically.

SUMMARY OF THE INVENTION In accordance with the invention this is accomplished in that the bobbin assembly is equipped with two threader studs arranged alongside one another, each of which receives one bobbin and with drive means for the inserted bobbin. In this manner the actual amount of time available for the sewing work is increased and the manipulations required for the exchange of bobbins is reduced to a tolerable condition. To that extent the invention provides that the threader stud is equipped with means for protecting the upper shell against rotary and axial displacement and that the driver on the threader stud is journaled for free rotation and can be coupled with the bobbin disposed in the top shell or bobbin case, as well as also with a driving member.

For the further simplification of the operation during bobbin exchange and for reducing the required handling to the absolute minimum the invention furthermore provides that the bobbin removed from the looper together with the top shell is threaded within this top shell.

In order to place the top shell with the empty bobbin that must be removed from the looper always in the same position of the bobbin assembly onto the threader stud, and subsequently, also always be able to remove the top shell with the threaded bobbin from another predetermined position of the threader stud, the two threader studs are arranged in a preferred embodiment of the invention in diametrically opposite positions upon a rotatably journaled disk which can be coupled with the driving member. The driving member is c'onnected with two coupling elements, one of which can be al' ternately coupled with the disk or in predetermined positions of the disk, the other with one of the catchers or drivers.

In a particularly advantageous embodiment of the invention the bobbin assembly has a thread guiding tube as a thread guiding means, the free end of which that guides the thread can be placed between the flange of the bobbin and is movable parallel to the axis of the bobbin and thereby engages the core of the bobbin firmly.

With these means which may also be employed with threaders known heretofore a reliable application of the first turns of the thread which extends over the diameter of one of the flanges of the bobbin onto the core of the bobbin is possible. Besides, the thread is guided to the lowest position of the surface of the threading cross section and finally the end of the thread guiding tube which moves away from the axis of the bobbin as the thread diameter grows provides the impulse for disconnecting the thread winding operation. v

Advantageously the thread guiding member is supported on a pivot axis for limited pivotal movement, which axis is supported by an axis of rotation disposed perpendicularly thereto and parallel to the threader stud in the supporting plate of the threader assembly, upon which axis an abutment member is adjustably secured which as apredetermined position of rotation is exceeded releases an abutment pin which disengages the coupling element that can be coupled with the driver and simultaneously positions the coupling element that can be coupled with the disk, which is connected with a disconnecting lever, that projects into the path of movement of the top shell that is placed upon the threader pin.

For the automatic insertion of the thread of the thread bobbin under the tension spring and into the threading eye of the top shell during rotation of the threader pin from the threading position to the position of readiness, the two threading pins each carry a pinion, which are in engagement with a toothed gear that is stationary on the supporting plate and in addition,

the abutments are connected with a pivotable lever held in an end position by a spring which projects into the path of movement of a control element arranged on the disk.

BRIEF DESCRIPTION OF THE DRAWINGS Further advantageous features, objects and details of the invention will become apparent from the embodiment of the new threader assembly illustrated in the accompanying drawings in which:

FIG. 1 is a perspective illustration of the head of a sewing I I DESCRIPTION OF PREFERRED EMBODIMENTS FIG. 1 shows the head 1 of the sewing machine with the externally visible components of the sewing tools, such as the take up lever 2, needle bar 3 with needle 4 and presser bar 5 with presser foot 6.

Underneath the work plate 7 the looper 8, for example of the double step stitch type, with the top shell or bobbin case 9 is located which is driven in a manner to cooperate with the needle 4. The shell 9 carries the tubular stud 10 FIG. 2 which slidably fits the center pin 11 of the bottom casing 12 journaled in the looper 8. The stud l0 accommodates the bobbin 15 that consists of a core 13 and flanges 14, which flanges are each provided with a slot 16 proximate the core 13.

The center pin 11 is provided proximate its free end with a latching groove 17 for the conventional latch slide 18 of the top shell 9, which slide is spring biased.

The circumferential wall 19 of the top shell 9 carries the tension spring 20 which covers the end of a thread slot 22 that extends from the edge 21 of the circumferential wall 19 to underneath the tension spring 20.

The cutout portion in the circumferential wall 19 which permits penetration of the needle into the looper 8 is limited on one side by a thread guiding edge 23 which extends obliquely with respect to the border edge 21. A thread eyelet 24 is provided in the upper part of the front end of the top shell 9 which receives thread through an angularly'offset slot 25.

The free end of the stud 10 of the top shell 9 is provided with a milled incision 26.

The head 1 of the sewing machine is closed or covered by a plate 27 which constitutes the supporting plate for the bobbin threading assembly. Plate 27 has secured to it a pinion 28 (FIG. 3) provided with a hub 29 which carries a supporting disk 30 provided with teeth circumferentially thereof. The disk supports two diametrically oppositely disposed sockets or sleeves 31, in each of which a bobbin threading shaft 32 is received. Each shaft 32, which is provided at its free end with an annular groove 33. is secured against axial displacement at one end by a collar 34 which rests against the sleeve 31 and at the other end by a pinion 35 mounted on an end of the threader shaft 32 extending through the disk 30. The number of the teeth of the pinions 35 to the number of teeth of the pinion 28 with which they are in engagement are at a ratio of 1:3. In addition to the collar 34 each threader shaft 32 is also provided with a stop pin 36 which extends perpendicularly to the longitudinal axis.

Each of the sleeves 31 has a catcher or driver 37 which is axially displaceable and freely rotatable. which at its front side that faces the disk 30 presents an annular groove 38 which receives a pressure spring 39 that is biased against the disk 30. The outer surfaces of the catchers 37 are provided with circular grooves 40 into each of which a rubber ring 41 is placed that projects beyond the diameter of the respective outer circular wall.'An annular groove 42 is milled into the free end surface of the catchers 37 which is confined between the outer annular wall 43 and an inner annular wall 44. The depth of the outer annular wall 43 in this connection is greater than that of the inner annular wall 44.

In the annular groove 42 the one end of a flat arcuately shaped leaf spring 45 is secured. The other end of the leaf spring 45 is in the form of an angularly offset catcher tongue 46.

The bearing bore of the catcher or driver 37 is bored up to an annular shoulder 47 which under the effect of the pressure spring 39 rests against the collar 34 of the threader shaft 32. Laterally of the catchers 37 two diametrically opposite thread cutters 48 (FIG. 1) are secured to the disk 30, each of which has a lateral guiding edge 49 and a cutting edge 50 which is joined thereto in V-shaped manner.

A pot-shaped brake disk 51 mounted onto the hub 29 (FIG. 3) of the pinion 28 is pressed against disk 30 by means of a spring disk 52 which is supported against a screw 53 threadedly received in the hub 29.

A sleeve 55 is rotatably journaled in the plate 27 by means of a bolt screw 54 (FIG. 5) and which has secured to it an abutment member 56. The abutment member 56 presents on one side an arcuately shaped edge 57 and an obliquely declining edge 58. In addition the sleeve 55 carries an adjusting ring 59 which has secured in it a pin 60 and one end of a torsion spring 61 that is disposed upon the sleeve 55, and the other end of which is in engagement with a lever 62 that is loosely supported on the sleeve 55 and which it turns for resting an abutment arm 63 angularly offset from the lever 62 against the pin 60. Two lugs 64 are secured to the end of the sleeve 55 which serve for journaling a hollow shaft 65. The shaft 65 is connected with an arm 66 which projects between two liiniting abutments 67 secured to the lever 62. A rocking lever 68 is clamped to the shaft 65, the free end of which supports the thread guide tube 69. The sleeve 55 with its lugs 64 is loosely journaled on the bolt screw 54 which is threadedly secured to the plate 27. Thus the rocking lever 68 can turn about the bolt screw 54 as well as about the shaft or axle 65.

On a pin 70 secured to the abutment member 56 (FIGS. 5,7 and 8) one end of a tension spring 71 is secured whose other end engages an abutment pin 72. The pin 72 is secured to a double lever 74 mounted above the disk 30 by means of a bearing hub which is not visible, upon a threaded bolt 73 secured to the plate 27. The pin 72 in this connection rests against the edge 57 of the abutment member 56 and upon counterclockwise turning of the sleeve 55 comes to rest behind the edge 58 of the abutment member 56. A pin 75 secured in the plate 27 serves for limiting the movement ofthe abutment member 56 during this rotation.

A lever arm.76 is journaled upon the bearing hub of the double lever 74, the free end of which supports a bearing eye' 77 which projects into a bore 78 in the double lever 74, as well as into a slot 79 in the plate 27. In the bearing eye 77 is journaled a shaft80 to the end of which that projects into the interior of the machine a cord pulley 81 is secured and whose other end carries a knurled knob 82 as a friction drive means that can be coupled with the rubber rings 41 of the drivers 37.

A torsion spring 83 (see also FIGS. 7 and 8). which at one end engages the bearing eye 77 and at the other end a screw 84 secured to the double lever 74 pivots the lever arm 76 counterclockwise until the bearing eye member 77 rests against the lower edge of the bore 78 which has a slightly larger diameter than the bearing eye member 77.

The double lever 74 is connected by way of a link 85 with a lever 86 which is pivotally secured on the plate 27 by means of a screw 88 that projects through a bearing sleeve 87 of the lever 86. An arcuately shaped arm 89 is connected with the bearing sleeve 87 which, at its free end, carries a grip member 90 and between its ends an angularly shaped safety member 91. A pull spring 92 is hooked onto the lever 86, the other end of which is secured to the plate 27.

A shaft 94 is journaled in a bearing boss 93 in the plate 27 (FIG. 3) and is axially secured by means of a collar'95 that rests against the boss 93 and by a cord pulley 96 secured on the shaft 94 that projects into the interior of the machine. The collar 95 has an eccentric crank stud 97 upon which a pawl 99 is journaled that is axially secured by means ofa latch disk 98. A torsion spring 100 which is disposed around the bearing boss 93, which at one end is in engagement with the plate 27 and with its other end with the pawl 99 presses the pawl 99 against the teeth of the disk 30. The pawl 99 (FIG. 7) carries a pin 102 which cooperates with one arm of lever 101.

A double armed lever 103 (FIGS. 6 to 8) journaled on the plate 27 is provided at one of its ends with two angularly offset abutments 104 and 105, of which abutment 104 extends into the path of movement of the pawl 99, and the other abutment 105 into the path of movement of the top shell or bobbin case 9 mounted upon the, threader shaft 32. The other end of lever 103 is in the form of a grip 106.

A further cord pulley .107 which is a driven member is rotatably secured on the plate 27 between the two cord pulleys 81 (FIGS. 3 and 4) and 96. This driven member 107 car ries a drive arm 108 provided with a plastic coating or the like 109 for noise suppression, and projects into the path of movement of the needle bar drive pin (not shown) which is provided in the sewing machine and executes a circular movement, and the driven member 107 is carried along by this movement. The possibility exists, of course, to drive the driven member or cord pulley 107 by any other suitable member that rotates during the operation of the sewing machine.

A belt 110 which runs over the three cord disks 81, 96 and 107 serves for transmitting the driving movement of the cord pulley 107 to the two shafts 80 and 94;

A thread 111 (FIGS. 1, 7 and 8) is fed through axle 65 to thread guide tube 69 from a thread supply (not shown) by way of a thread brake (likewise not shown), through a hollow thread guiding tube 1 l2 projecting through the plate 27.

The arrangement operates as follows:

As the bobbins are changed the top shell 9 together with the empty bobbin is removed from the bottom casing 12 of the looper 8 and placed upon the upper empty threader shaft 32 of the threading assembly. In this connection the latching slide 18 of the top shell or bobbin case 9 engages the annular groove 33 of the threader shaft 32. The incision 26 provided on the stud 10 of the upper shell or bobbin case 9 into which the pin 36 becomes engaged insures the accurate insertion of the shell 9. The bobbin 15 disposed in the shell 9 comes to rest against the annular wall 43 of the driver 37 and displaces the same against the effectof the pressure spring 39 in the direction of the disk 30. Simultaneously the thread 111 which leads out of the thread guide tube 69 by way of the thread cutter 48 into the shell 9 disposed on the lower threader shaft 32 is clamped between the one flange 14 of the bobbin l5 and the annular wall 43 of the driver 37.

FIG. 8 shows the threading assembly after the shell 9 with empty bobbin hasjust been put in place.

The operator now turns on the threading assembly by pressing the arm 89 downwardly by means of the grip 90. Thus the lever 86 is shifted which by way of the link 85 and the double lever 74 swings away the abutment pin 72 from the edge 58 of the abutment member 56. This member rotates under the effect of the pull spring 71 in counterclockwise direction until the thread guiding tube 69 secured to the rocking lever 68 rests against the core 13 of the bobbin 15. Upon release of the grip 90 the abutment pin 72 engages the edge 57 of the abutment member 56 under the effect of the pull spring 92 and thus prevents complete return of the arm 89 and thereby also of the safety member 91 which in the disconnection position of the threading assembly rests in front of the shell 9 when the same is disposed in the lowest position of its path of movement.

The operator may now loosen the shell 9 which is carried on the lower threader shaft 32 by turning away its latching slide 18, remove it together with the filled or threaded bobbin 15 and insert it in the looper 8. At the same time the section of thread which extends from the upper to the lower bobbin 15 by way of the edge 50 is severed. FIG. 1 illustrates the position of the threading assembly in this connection.

As the machine is started the drive arm 108 with the cord pulley 107 is caused to rotate by means of the needle bar drive stud 109a which comes into engagement with the plastic coating 109. The cord pulley 107 causes a rotation of the two cord pulleys 81 and 96 by means of the belt 110.

in the position of the double armed lever 74 in which it is held by the abutment 'pin 72 the lever arm 76 is pressed downwardly by the torsion spring 83 until the knurled knob 82 engages the rubber ring 41 of the driver 37 as shown in FIG.

The cord pulley 81 therefore carries along by its rotation and by way of the knurled knob 82 connected with it the driver 37 which is freely rotatable upon the upper threader shaft 32. As the driver is driven the driver tongue 46 of the leaf spring 45 becomes seated in the slot 16 of the adjacent flange 14 of the bobbin 15 and takes the same along during its further rotation.

As a result the part of thread 111 which emerges from the thread guiding tube 69 whose end which is clamped between the bobbin 15 and the annular wall 43 of the driver 37 is wound upon the core 13 of the bobbin 15.

The limitation of the lateral pivoting of the thread guide tube 69 results from the two limiting abutments 67 for the arm 66 which is securely connected with the pivoting lever 68. This limitation of the lateral movement of the thread guide tube 69 is necessary so that the same is reliably introduced during the starting operation for threading between the flanges l4 ofthe bobbin 15.

As the thread coil grows upon the bobbin 15 the pivot lever 68 swings upwardly and thus pivotally moves the stop member 56. As the bobbin 15 is threaded the rotation of the stop member 56 has progressed so far that the abutment pin 72 falls in behind the edge 58 and turns the stop member 56 until it engages the pin 75. Simultaneously the thread guide tube 69 is lifted out of the area of the bobbin 15 and of the shell 9.

The introduction of the abutment pin 72 takes place under the effect of the pull spring 92 by swinging of the double lever 74 in counterclockwise direction while the knurled knob 82 journaled on the lever arm 76 isswung away from the rubber ring 41 of the driver 37 and no longer drives the same.

Furthermore, the double lever 74 turns the lever 86 by way of the link 85 so that its arm 101 releases the pin 102 of the pawl 99.

The driven cord pulley 96 turns the crank stud 97 by way of shaft 94 so that the stud 97 effects a lifting movement of the point of the pawl 99 which is in engagement with the teeth of the disk 30. The pawl upon its release now drives the disk intermittently in counterclockwise direction.

As the disk 30 rotates the threader shafts 32 additionally rotate counterclockwise due to the engagement of their pinions 35 with the toothed wheel 28 that is fixedly mounted on the plate 27. As a result, the shell or case 9 which is on the upper threader shaft 32 is turned together with the threader shaft 32. By means of this rotation the thread 111 which extends from the bobbin 15 to the thread guide tube 69 is conducted away from the thread guide edge 23 to the edge 21 of the circumferential wall 19 of the shell 9. With progressing rotation ofthe disk 30 the rubber ring 41 of the catcher 37 engages the lever 62 which turns oppositely to the effect of the torsion spring 61 and thereby swings away the rocking lever 68 from the plate 27 and guides the thread 111 as the rotation of the shell 9 progresses along its borderedge 21 and'then into the thread slot 22 and thence below the tension spring 20.

During further rotation of the shell 9 the thread 111, as shown in HQ. 7, is guided into the slot 25. past the latch slide 18 and threaded into the thread eye 24 during the further rotation.

The lever 62 is of such length that it only moves away from the driver 37 when the disk 30 has rotated so far that the section of the thread 111 which extends between the thread guide tube 69 and the top shell 9 arrives in its position of rest on the leading edge 49 of the thread cutter 48 as the rocking lever 68 swings back under the effect of the torsion spring 61.

The disk 30 rotates under the effect of the pawl 99 so long as the uppershell or case 9 contacts the abutment of the lever 103 and this lever while rocking with its abutment 104 brings the pawl 99 out of the range of the teeth of the disk 30. For this condition the thread 111 extends from the thread eye 24 of the shell 9 by way of the lead edge 49 of the thread cutter 48 to the thread guide tube 69 and is disposed simultaneously in front of the annular wall 43 of the driver 37. The threading operation is thus completed.

As a new shell 9 with an empty bobbin 15 is placed upon the threader shaft 32 of the threader assembly which is now located on top the thread 111 is clamped in the manner described above between the annular wall 43 of the driver 37 and the bobbin l5. Simultaneously it is pressed automatically by the leading edge 49 of the thread cutter 48 behind the V- shaped edge 50.

As soon as the shell 9 is withdrawn with the threaded bobbin 15 from the lower threader shaft 32, upon previous actuation of the threading assembly by pressing down the grip 90, the section of the thread 111 which extends to the lower bobbin 15 is severed from the thread 111 clamped by the upper bobbin 15, by the cutting edge 50 with the correct starting length required for beginning the sewing operation.

I claim:

1. Bobbin threading and winding device for sewing machines comprising a supporting disk mounted on the machine, a pair of threader shafts supported on said disk, a pair of drivers each rotatably mounted on one said shaft, each said shaft being adapted to receive a bobbin disposed in a bobbin case, rotary and axial movement opposing latch means intermediate said shaft and said bobbin case, first coupling means coupling one said bobbin on one said bobbin shaft with one corresponding said driver, drive means operative to drive said drivers independently of one another, manually operable second coupling means operative for selective coupling of said drive means with said drivers, and thread guide means determining the supply of thread upon a bobbin and effective to uncouple said second coupling means in response to a predetermined quantity of thread on one said bobbin.

2. Bobbin threading and winding device in accordance with claim 1, including a base plate rotatably supporting said disk, and said disk supporting said bobbin shafts diametrically op posite from one another.

3. Bobbin threading and winding device in accordance with claim 1, where said second coupling means comprise two coupling elements, one of which effects coupling with one said driver in a predetermined position of said supporting disk, the other being adapted for coupling with the supporting disk and connected with said one coupling element for automatic coupling with said one supporting disk by said thread supply determining guide.

4. Bobbin threading and winding device in accordance with claim 3, including disconnecting means connected with said supporting disk operable in a predetermined position of said supporting disk to uncouple said other coupling element.

5. Bobbin threading device in accordance with claim 2, where said drive means include a driven member supported on said plate and said first coupling means including pawl means adapted to drive said disk. and said second coupling means in' cluding a friction drive means operative to drive one said threader shaft.

6. Bobbin threading device in accordance with claim 5, where said thread feeding means includes a rocking lever pivotally supported at one end and supporting a thread guide member at its other end, lever supporting means carried on said supporting plate, said bobbin having a core on which thread is wound and said guide member having a free end adapted for guiding the thread transversely of said core and being movable into engagement with said core.

- 7. Bobbin threading device in accordance with claim 6, where said lever supporting means include a sleeve rotatably journaled on said supporting plate and presenting a pair of lugs engaging the other end of said rocking lever, a shaft extending through said lugs and said other end of said rocking lever, said shaft presenting a limiting arm. a limiting lever disposed on said sleeve and presenting a pair of abutments for engagement by said limiting arm, an adjustable abutment member on said sleeve, a spring biased double armed lever disposed on said plate above the uppermost said driver having an abutment pin at one end and rotatably supporting said second coupling device for engagement with and to rotate said driver with a bobbin, and upon release of said pin by said abutment member to disengage said driver, and the first said Coupling device including said pawl being disposed on said plate below said lowermost driver, linking lever means connecting said first coupling device to said double armed lever, a disconnecting lever associated with said first coupling element, said disconnecting lever extending into the path of movement of a bobbin case mounted on said lowermost catcher.

8. Bobbin threading device in accordance with claim 7, including a pinion on each said driver, a toothed gear supported on said plate intermediate said pinions and in engagement therewith, and said limiting lever having a free end extending over said disk, and a spring biasing said limiting lever in its end position. I

9. Bobbin threading device in accordance with claim 7, including a thread cutter proximate each said threader shaft and driver, said cutter having a V-shaped edge adapted to grip a thread extending between said thread guide member and a filled bobbin. 

